1. Field of the Invention
The present invention relates to a substrate voltage generation circuit for a semiconductor device, and in particular to an improved substrate voltage generation circuit for a semiconductor device which is capable of increasing a substrate power supply capability and decreasing the amount of current consumed by a charge pump by pumping a word line driving voltage in a burn-in mode and adding a mode judgement circuit.
2. Description of the Conventional Art
FIG. 1 illustrates a conventional substrate voltage generation circuit for a semiconductor device, a conventional substrate voltage generation circuit for a semiconductor device includes an oscillation unit 1 for generating a voltage OSCV having a predetermined frequency, a first charge pump 2 for pumping an output voltage OSCV from the oscillation unit 1 and generating a substrate voltage VBB, a burn-in detection unit 3 for recognizing a burn-in mode and outputting a signal .phi. based on the recognized mode, and a second charge pump 4 for pumping the signal .phi. and generating a substrate voltage VBB.
The operation of a conventional substrate voltage generation circuit for a semiconductor device will now be explained with reference to the accompanying drawing.
The oscillation unit generates a voltage OSCV having a predetermined frequency. The first charge pump 2 pumps the voltage OSCV and generates a substrate voltage VBB, and the substrate voltage VBB is applied to a semiconductor device. At this time, the level of the output signal .phi. from the burn-in detection unit 3 is low.
In addition, when the normal mode is changed to the burn-in mode, the burn-in detection unit 3 outputs a high level output signal 100 , and the second charge pump 4 pumps the output signal .phi. and outputs the same to the substrate voltage VBB.
The level of the substrate voltage VBB pumped by the second charge pump 2 is higher than the level of the substrate voltage VBB pumped by the first charge pump 2 in the normal mode.
In the burn-in mode, a high level substrate voltage VBB is generated by using an additional charge pump, so that it is possible to prevent characteristic degradation such as a latch-up, etc. which occurs due to the substrate voltage VBB in the burn-in mode.
However, in the conventional substrate voltage generation circuit for a semiconductor device, since the charge pump which is operated in the burn-in mode is additionally used, the amount of current which is used for two charge pumps is increased, and since two identical hardware are used, the efficiency of the circuit is deceased.